Strutural effect of cationic surfactant on heavy metal removal capacity of raw sepolite

Abstract

Important features like the change of surface properties from hydrophilic to hydrophobic and the change of surface charge from negative to positive, enable the production of organosepiolites from sepiolites, their use in various processes including adsorption of organic pollutants, removal of heavy metal contaminants and water treatment processing.
Organo-clays have been synthesized using Turkey (Sivrihisar/Eskişehir) smectite and the cationic surfactant hexadecyltrimethylammonium bromide (HDTMAB). Moreover, the removal characteristics of Cd²⁺, Cu²⁺ and Pb²⁺ ions from aqueous solution by prepared organoclay have been investigated. The changes in the surfaces and structures of the smectites modified with HDTMA surfactant have been characterized using X-ray diffractometry (XRD), Fourier transform infrared spectroscopy (FTIR), Brunauer-Emmett-Teller (BET), Thermogravimetric analysis (TG), Total organic carbon (TOC) and particle size analysis. The XRD patterns show that the intergallery distances of the raw sepiolite increase with the surfactant loading. The FTIR measurements are used to indicate the interactions between the raw sepiolite surface and the HDTMA cations. The BET surface area of the organosepiolites decrease significantly after the modification, due to the coverage of the pores of the raw sepiolite. The thermogravimetric peaks (DTG) in the range between 350-450°C depends on the surfactant loadings and provide the evidence for the formation of the multilayers on the sepiolite surface. The organosepiolite sample that was labeled 1.5h-2CMC, is chosen for next heavy metal adsorption studies.